We study charged hydrodynamics in a periodic lattice background.Fluctuations BCAA are Bloch waves rather than single momentum Fourier modes.At boundaries of the unit cell where hydrodynamic fluctuations are formally degenerate with their Umklapped copy, level repulsion occurs.
Novel mode mixings between charge, sound, and their Umklapped copies appear at finite chemical potential - both at zero Washing Machine Hose Clamp and finite momentum.We provide explicit examples for an ionic lattice, i.e.
a periodic external chemical potential, and verify our results with numerical computations in fluid-gravity duality.